(a) Field of the Invention
The present description relates to a thin film transistor (TFT) array panel and a manufacturing method of the same.
(b) Description of the Related Art
Liquid crystal displays (LCDs) are one of the most widely used flat panel displays. An LCD includes a liquid crystal (LC) layer interposed between two panels provided with field-generating electrodes. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer, which determines orientations of LC molecules in the LC layer to adjust polarization of incident light.
An LCD including two panels respectively provided with field-generating electrodes, wherein one panel has a plurality of pixel electrodes in a matrix and the other has a common electrode covering the entire surface of the panel, dominates the LCD market.
The LCD can display images by applying a different voltage to each pixel electrode. For this purpose, thin film transistors having three terminals to switch voltages applied to pixel electrodes are connected to the pixel electrodes and gate lines to transmit signals for controlling thin film transistors, and data lines to transmit voltages applied to pixel electrodes are formed on a thin film transistor (TFT) array panel.
The gate lines and data lines of the TFT array panel preferably comprise a conductive material having low resistivity such as aluminum (Al) or an Al alloy to reduce signal delay. However, Al is vulnerable to a chemical or physical attack and has a bad contact characteristic with indium tin oxide (ITO). Accordingly, the gate lines and data lines are formed to have double or triple layers including Al or an Al alloy layer and another metal layer having a good contact characteristic with ITO and strong resistance to a chemical or physical attack. Molybdenum (Mo) is one of such metals having a good contact characteristic with ITO and strong resistance to a chemical or physical attack. A Mo-containing layer is useful in the formation of signal lines along with an Al-containing layer because the Mo-containing layer and the Al-containing layer can be simultaneously patterned by etching.
However, when data lines and drain electrodes include the Mo-containing layer, an off current of the TFTs is increased, thereby degrading the image quality of an LCD.